Barack Obama defends 'just war' using drones

President Barack Obama has defended the use of drones in a "just war" of self-defence against deadly militants and a campaign that had made America safer.

In a wide-ranging speech on a programme shrouded in secrecy, he said there must be "near certainty" that no civilians would die in such strikes, BBC reports.Barack Obama

In a renewed push to shut Guantanamo Bay, he said he had lifted a moratorium on prisoner transfers to Yemen.

Mr Obama also defended the use of drones to kill four US citizens.

"We are at war with an organisation that right now would kill as many Americans as they could if we did not stop them first," he said in Thursday's address at the National Defense University in Washington DC.

"So this is a just war - a war waged proportionally, in last resort, and in self-defence."